Could someone help me with these two questions?? thank you

What is the algorithm for building a binary tree program

Nathan wants to create multiple worksheet containing common formatting styles for his team members. which file extension him to save these worksheets? nathan to create multiple worksheets with common styles. he needs to save them with the extension.

2pointswho was mikhail gorbachev? oa. a russian leader who opposed a coupob. a polish leader who founded the labor union "solidarityoc. a soviet leader who called for a closer relationship with the unitedstates, economic reform, and a more open societyd. a soviet leader who called for more oppression in the soviet union